Process for the manufacturing of metallic diaphragms for talking machines, telephoneand wireless apparatus, etc.



July 16, 1929. REINERT 1,721,038

PROCESS FOR THE MANUFACTURING 0F METALLIC DIAPHRAGMS FOR TALKING MACHINES, TELEPHONE AND WIRELESS APPARATUS, ETC Filed June 23, 1927 INVENTOR. 1? Rainer ATTORNEYS.

Patented July 16, 1929,

UNITED STATES PATENT OFFICE.

ROBERT REINERT, OF LA CHAUX-DE-FONDS, SWITZERLAND.

PROCESS FOR THE MANUFACTURING OF METALLIC DIAPHRAGMS FOR TALKING IMA- CI-IIINES, TELEPHONE AND WIRELESS APPARATUS, ETC.

Application filed June 23, 1927, Serial No. 200,972, and in Germany June 26, 1926.

Diaphragms for talking machines are generally made either of mica or-of metal. Easy as it can be machined, the metal offers the disadvantage that faults in the diaphragms are due to the manufacturing process involved. In fact, metallic diaphragms, after having been cut into blanks out of previously rolled sheets, pass, for the most of the part, beneath the die of a press for receiving either a definite shape or a determined name or fig ure. During the rolling, cutting out and pressing, notable stresses arise in the body of the diaphragms, and, since varying most considerably from one blank to the other, prevent the mass production of diaphragms reproducing each tone with the same purity.

My invention relates to an improved method of making metallic diaphragms for talking machines, telephones and the like and its object is to overcome the above mentioned inconvenience. According to this method a metal disk is first given the desired shape and after all mechanical operations necessary therefore have been done the disk is placed between two blocks of which the surfaces coming into contact with the disk have the same shape as the two respective surfaces of the disk which is then heated and afterwards slowly cooled whereby the internal stresses in the metal due to said mechanical operations are neutralized. In certain cases it may be necessary to slightly hammer some of the disks after the heat treatment in order that all the diaphragms acquire a uniform dept-h of sound.

In the drawing, Figure 1 is a plan view and Fig. 2 a side view of a blank of metal from which the diaphragm is made. Fig. 3 is a sectional view of a finished diaphragm with a flanged edge. Fig. 4C is a sectional View of a diaphragm with a central concavity. The invention may be carried out as follows:

After having been cut out of a rolled sheet of metal, the blank shown in Fig. 1 passes beneath the die of a press where it receives the shape illustrated in Fig. 2 or in Fig. 3. For neutralizing the internal stresses due to rolling, cutting out and pressing twenty diaphragms are stacked between two blocks of iron, the inside surfaces of which have, the

one, the top and, the other, the bottom shape of the diaphragm. Blocks and diaphragms are firmly attached, heated,the temperature ranging from 300 C. to 400 0., if the dia phragms are made of an aluminium alloy, and put to cool slowly. The heating temperature ought to reach but the point necessary for the neutralizing of the internal stresses, since, above that point, the diaphragms run the risk of getting their elasticity diminished to their detriment. 1

As a matter of fact, diaphragms handled in such a way reproduce the tone with a greater purity than the ordinary ones up to now on the market. Furthermore, it is to be noticed that, when made gently to vibrate, all diaphragms will give nearly the same sound (provided of course that they are made of the same material and show both'the same shape and the same dimensions). Should some diaphragms not give the identical sounds, it is easy to correct fully the differences by hammering slightly the one or the other diaphragm. Experience tells how strong the strokes of hammer are to be and which part of the diaphragm should be hammered over. In that way it is possible to obtain diaphragms of the same depth of tone.

I claim:

1. The method of making metallic diaphragms for talking machines, telephones and the like, Which consists in giving a disk of metal the desiredfinal shape of the diaphragm, and after all the necessary mechanical operations therefor have been done, in placing the disk between two blocks, the surfaces t iereof coming in contact with the disk having the same shape as the surfaces of the disk, heating the disk, and permitting it to cool slowly, whereby the internal stresses of the metal due to said mechanical operations are neutralized.

2. In the method of making metallic diaphragms according to claim 1 the additional step of slightly hammering the disk after the heat treatment whereby the depth of sound can be adjusted.

In testimony whereof I ailix my signature.

ROBERT REINERT. 

